The invention relates to a process for the entrained bed catalytic conversion of a charge incorporating at least one oxygen or oxygen-containing compound and more specifically at least one alcohol, such as methanol and/or at least one ether oxide, such as dimethyl ether and an apparatus for performing this process incorporating at least one co-current cyclone separator permitting the very rapid separation of the solid particles and the gases.
This process is more particularly applied to the production of olefinic hydrocarbons, particularly for petrochemical uses and largely constituted by compounds having 2 to 4 carbon atoms in their molecule, in the presence of a catalyst, such as a zeolite, circulating in an entrained bed reactor. A particular use given in exemplified manner here is the catalytic conversion of methanol into ethylene and/or propylene-rich hydrocarbons. The technical background is illustrated by U.S. Pat. No. 4,197,418.
One of the essential factors in the selective production of light olefins and more particularly ethylene and/or propylene by conversion of methanol is controlling the contact time between the charge and the catalyst. This contact between the charge and the catalyst must be both short and uniform (or regular) in time, which imposes a contacting uniformity and speed between the catalyst grains and the gaseous or liquid charge. It is therefore important to more particularly control the charge quantity introduced in conjunction with the catalyst quantity with which it comes into contact, while keeping constant the contact time between the charge and the catalyst in order to bring about the optimum selectivity in the desired ethylene compound or compounds. In the absence of such a control, the tendency of the reaction is to lead to a wide range of saturated and unsaturated hydrocarbons generally extending from methane to hydrocarbons having up to or more than 10 carbon atoms in their molecule and such as those conventionally constituting the naphtha cut.
In the methanol conversion processes using the entrained bed procedure described in the prior art, there is usually an insistence on the importance of optimizing and controlling the contact time between the catalytic particles and the charge. As is e.g. stated in U.S. Pat. No. 4,229,608, this contact time must be relatively short. However, no reference is made to the use of a separation system appropriate for allowing an effective, rapid separation of the solid particles and the gases containing the reaction products.
The association of well chosen operating conditions and an ultra-fast separation of the catalytic particles and the gaseous products including the conversion products in particular makes it possible to significantly improve the selectivity with respect to the desired ethylene compound or compounds, which was not the case in the prior art, such as e.g. that described in U.S. Pat. No. 4,046,825.